The present invention relates to a packaging box, and in particular to packaging box having a structure allowing no contingent tear.
Generally, the structure of packaging box forms a body of box in a quadrangular cylindrical body with a front and back plate and a left and right side plate and adopts a structure to provide a cover plate and base plate, which blocks off openings formed respectively at opposite top and bottom ends of the cylindrical body, to lead connectively to the opposite top and bottom sides of the front plate forming the cylindrical body allowing the cover plate and base plate by folding the same to open and close the openings.
Among these packaging boxes, particularly if the use is for packaging box to hold medical supplies or the like, it is considered necessary to provide a tear prevention function in order to prevent such risks as mischief or pilferage made against the contents.
For this purpose, pharmacists add a structure to give a function of tear or conversion prevention to the box and pay a lot of attention to the cover plate and base plate portion which can most easily be tricked for tearing.
The prior structure for preventing tear and conversion, however, mostly adopts a double construction in the cover plate and base plate portion thereby a tear mark could easily be detected if the box should be torn, but in this case, besides the structure being complicated, it is a defect that a risk still remains for the contents being taken out without giving any damage to the cover plate or base plate when they are torn carefully by means of a sharp knife or the like at the portion (overlap width) on which an adhesive is spread.